8 - Copy the /dev/ttyS0 to the location where it will be referenced. This is an imitation of the delivered method and prefereble to changing ownership/permission on /dev/ttyS0.cp -R /dev/ttyS0 /var/lib/ups/ttyS0

9 - Change the owner of the new one so that NUT can use it.chown nutups:nutups /var/lib/ups/ttyS0